Traditionally, satellites for transmitting numerous television channels are stationed in orbit, generally over the equator, and remain substantially stationary with respect to the Earth. Signals from any single satellite may contain many channels, however, a signal from any one satellite will not contain all available broadcasts. Commonly, signals from as many as three or four satellites may be desirable to serve a single viewer or a single building complex.
Satellite signals are typically collected using a Digital Sky Highway antenna, or DISH antenna, aligned with the target satellite. DISH antennae are generally shaped parabolically to focus the signal at a focal point. A Low Noise Block (LNB) receptor is placed at the focal point of the DISH antenna to receive the radio wave signals and transform them into high frequency electrical signals. The signals are divided into two components; a horizontal component and a vertical component.
Various system configurations for transmitting signals from multiple satellites to multiple receiving units exist. Furthermore, local channels are often desired, and thus such systems include means for transmitting signals from a terrestrial antenna to the same receiving units. At high frequencies, signal splitters are undesirable due to substantial power loss. Therefore, many of these configurations require multiple DISH antennae, or other costly equipment.
The most basic system configuration for transmitting signals from a single satellite and a single terrestrial antenna to a single receiving unit is shown in Prior Art FIG. 5. The system 10 includes a DISH antenna 15 having an LNB 20, and signal lines 25 connecting the LNB 20 to an AB switch 30. The AB switch 30 is typically a slide switch which must be manually operated. A terrestrial antenna 35 also provides a signal via signal line 40 to AB switch 30. The AB switch outputs a combined signal via line 45 which is decombined by decombiner 50, and received by receiving unit 55. This configuration is limited to providing signals to a single receiving unit, and must be manually switched between the satellite signal and the local signal.
This basic system is modified in Prior Art FIG. 6 to allow a single receiving unit to receive signals from two satellites and local channels. A second DISH antenna 16 having LNB 17 is added to the system. The three signals are fed into an ABC switch 32, which is typically a three-position slide switch. This system allows a single receiving unit to receive signals from two different satellites and local channels, however, the viewer still must manually switch between the two satellite signals and local channels.
System configurations for providing signals to multiple receiving units typically employ Digital Broadcast System (DBS) multi-switches having multiple input ports and either a single output port, or multiple output ports. DBS multi-switches are powered switches which have a poling cycle at which signals are sampled from different inputs. Caution must be taken to match the poling and circuitry characteristics of the multi-switches with the components of the system to produce desired results.
The Prior Art system shown in FIG. 7 illustrates the transmission of two satellite signals to two different receiving units without the need for a manual switching device. A signal component from each DISH antenna is fed into an input of each multi-switch 60 and 65. Both signal components are required in order to receive a usable signal, however, the signal from one signal component line is sent back up the same line and down the other line, enabled by power from the receiver. Thus, each multi-switch receives both signal components from both satellites. Adding further receiving units with such a system would require additional satellite DISH antennae.
Prior Art FIG. 8 illustrates a system configuration which enables signals from two satellites to be received by up to four receiving units using only two DISH antennae, and without the need for manual switching. This system makes use of dual LNB receptors 70 and 75. Satellite DISH antennae utilizing dual LNBs receive signals from two different satellites, and focus them to two dual LNB components respectively. Thus, each dual LNB has 4 signal component lines extending therefrom.
Prior Art FIG. 9 illustrates a system configuration in which signals from three satellites are transmitted to up to four receiving units. The system uses three DISH antennae and a powered multi-switch 80 receiving power from an external power supply 85. Adding more receiving units to this system requires further DISH antennae or other costly equipment.
Finally, Prior Art FIG. 10 illustrates a system configuration in which signals from up to four satellites and one terrestrial antenna are fed into a multi-switch having nine input ports and eight output ports. Up to eight receiving units will receive signals from all sources, however, adding additional receiving units requires additional DISH antenna, and such large multi-switch units are costly.
Solutions for serving multiple receiving units have focused around additional DISH antennae and expensive multi-switches having multiple ports which require complicated circuitry. The greater the demands on the system, the more costly and complicated it becomes. Therefore, an efficient system and method for transmitting multiple signals to multiple receiving units in which the switching is transparent to the viewer would be desirable.